Giant Sand, Bush Hall, London

The story of Giant Sand is a story of immense talent deliberately unfocussed. Conflicting impulses, relentless experimentalism and an addiction to irony have kept Howe Gelb's consistently interesting outfit on its toes for over 20 years now. The guitar-based music they produce is unclassifiable, but that never stopped anyone trying, and since Gelb is from Tucson and uses far-west riffs and themes, it has been dubbed "desert rock". Accordingly, once the band have slowly shuffled their way on to the stage and into a loose groove, the first line Gelb sings tonight is: "The desert is deserted." Such characteristic self-mockery lends an evening with Giant Sand a sense of enjoyable bonhomie, but it also adds an element of vague frustration.

The story of Giant Sand is a story of immense talent deliberately unfocussed. Conflicting impulses, relentless experimentalism and an addiction to irony have kept Howe Gelb's consistently interesting outfit on its toes for over 20 years now. The guitar-based music they produce is unclassifiable, but that never stopped anyone trying, and since Gelb is from Tucson and uses far-west riffs and themes, it has been dubbed "desert rock". Accordingly, once the band have slowly shuffled their way on to the stage and into a loose groove, the first line Gelb sings tonight is: "The desert is deserted." Such characteristic self-mockery lends an evening with Giant Sand a sense of enjoyable bonhomie, but it also adds an element of vague frustration.

The title of the band's latest album,
Giant Sand is All Over the Map, sums up Gelb's entire career, and even without concentrating on that triumphantly varied record, tonight's set takes in reggae, full-on rawk, cocktail jazz, knee-slapping country, punk and drive-time balladry - often in the course of a single song. In a way, it's a virtuoso performance, and it's good to see the new line-up working together so well - Gelb had been hit hard by the departure of Joey Burns and John Convertino, Giant Sand's rhythm section for most of the Nineties until the runaway success of their side-project, Calexico, started taking up too much of their time.

The musicianship on display is hugely impressive, with the three Danes who now form the core of the band (Gelb divides his time between Arizona and Aarhus) providing excellent slide guitar, bass and drums. As a guitarist, Gelb is a master at playing the same melody in different styles, venturing away from it into noise territory, and then pulling the whole thing back. His instinct for sketchiness and unorthodox phrasing makes rock-outs that could reach stadium-sized naff-ness in other hands sound powerful and exciting - especially when another Dane, Marie Frank, takes over the vocals.

A second guest vocalist is Scout Niblett, Giant Sand's hand-picked support. In his role as the 'godfather of alt.country' (definitely a calls-on-your-birthday kind of godfather, rather than a mafioso) Gelb loves to nurture new talent, and Niblett is one of the most original voices around. A gawky Staffordshire girl in a wig, she accompanies herself on drums part of the time. Though she sometimes shouts in an annoying performance-art way, her exuberantly loud but cute singing - especially when she swaps the drums for minimalist guitar-playing - is captivating.

Gelb, meanwhile, seems to regard singing into either of his two microphones as optional much of the time. This particularly detracts from the languid, brooding songs that characterised the band's 2001 masterpiece,
Chore of Enchantment, or "Classico", the stand-out track from
All Over the Map - but those are better heard alone on a summer afternoon, than standing in a crowded room anyway.

That said, the band do blend the slower numbers well into a set that also features big guitars, frenetic riffing and outbreaks of jovial silliness. The more rocking, guitar-driven numbers tend to dominate the latter part of the set, suggesting that this might be the most natural idiom for the current line-up to play. But perhaps it is precisely the endless chopping and changing that makes Giant Sand so cool and original. It certainly creates a feeling of adventurous happiness. But it can also give the impression that Gelb has already lost interest in what he is singing about before he's even opened his mouth.

Reviewers often give this band three-star reviews, but it would be a travesty to suggest that they are mediocre. They are brilliant - it's just that they could be even better.